Advance Mode Frame Packing; Advance Mode Frame Unpacking; Mux State Procedures - Motorola G24 Guide Developer's Manual

Advance Mode Frame Packing

The transmitter (referring to the sender of a frame) examines the frame between the opening and
closing flag sequences (including the address, control and FCS fields) and, following completion
of the FCS calculation, does the following:
•
When encountering protected characters, complements the 6th bit of the octet (XOR with
0x20).
•
Inserts a control escape octet immediately preceding the octet resulting from the above, prior
to transmission.

Advance Mode Frame Unpacking

The receiver (referring to the receiver of a frame) examines the frame between the two flag octets.
Upon receipt of a control escape octet, and prior to FCS calculation, it does the following:
•
Discards the control escape octet.
•
Restores the octet that immediately follows by complementing its 6th bit (XOR with 0x20).

MUX State Procedures

Valid channel indexes in MUX state are 0 to 4, where 0 is the index of the control channel and 1-4
are indexes of the information channels (IDLC).
The following table describes the basic procedures (Open/Close/Err) performed when the G24 is
in MUX state.
Unrecognized
Frames/Invalid Frames
SABMi Reception –
Channel Establishment
DISCi Reception –
Disconnect Channel
December 31, 2007
Table B-3: MUX State Procedures
Procedure
The G24 ignores unrecognized and invalid frames.
Upon receiving a SABMi frame (i = channel index), the G24 checks
whether i is within the valid range and is not already established. It them
tries to establish the new channel.
If the G24 succeeds, it sends a UA frame. If it is not successful, it sends
a DM frame.
Upon receiving a DISCi frame (i = channel index), the G24 checks
whether i is within the valid range and represents an open channel. If so,
the G24 attempts to close the channel.
If the G24 is successful, it sends a UA frame. If it is not successful, it
sends a DM frame.
Closing a channel hangs up any active CDSs. However, active voice
calls are not hung up, even after the IDLC is closed.
AT Commands Reference Manual
Appendix B: MUX
Description
B-5